Preparation of free sulfoximines by hydrolysis of N-(ortho- and para-nitrobenzoyl)-sulfoximines

ABSTRACT

wherein R1 and R2 each represent an aliphatic radical having from 1 to 3 carbon atoms, a phenyl radical or a monosubstituted phenyl radical, are produced by reacting a sulfoxide having the formula II: R1R2S O II wherein R1 and R2 are as described above, with an Oacylnitrobenzhydroxamic acid of the general formula III:   Novel intermediates having the general formula I: wherein R1 and R2 are as described above. The novel sulfoximines of this invention having formula I and the free sulfoximines having formula IV, produced by the novel process of this invention are useful as intermediates in the preparation of known, pharmacologically active N-substituted aminoalkyl-S,Sdiphenylsulfoximines.   wherein R3 represents methyl or ethyl. The above novel process is safe and easy to run without the usual precautions against spontaneous explosions required in prior art sulfoximine preparations. The novel N-(ortho- and para-nitrobenzoyl)sulfoximines of formula I may be hydrolyzed, under either acid or alkaline conditions to obtain free sulfoximines of the formula IV:   D R A W I N G

United States Patent [1 1 Herrmann et al.

1 PREPARATION OF FREE SULFOXIMINES BY HYDROLYSIS OF N-(ORTHO- AND PARA-NITROBENZOYL)-SULFOXIM1NES [75} Inventors: Wolfgang Dieter Herrmann,

Denzlingen; Peter Johannes Stoss, Wildtal; Gerhard Satzinger, Denzlingen, all of Germany [73] Assignee: Warner-Lambert Company, Morris Plains, NJ.

[22] Filed: Sept. 9, 1974 [2]] Appl. No: 504,013

Related US. Application Data [62] Division of Ser. No. 35l.ll2. April 13. I973v Pat.

[30] Foreign Application Priority Data Primary E.raminerDaniel E. Wyman Assistant Examiner-Thomas A. Waltz Attorney Agent, or FirmAlbert H. Graddis; Frank S. Chow; Anne M. Kelly [57] ABSTRACT Novel intermediates having the general formula 1:

[451 Nov. 11, 1975 wherein R and R each represent an aliphatic radical having from I to 3 carbon atoms. a phenyl radical or a monosubstituted phenyl radical, are produced by reacting a sulfoxide having the formula II:

wherein R and R are as described above. with an O-acylnitrobenzhydroxamic acid of the general formula lll:

wherein R represents methyl or ethyl The above novel process is safe and easy to run without the usual precautions against spontaneous explosions required in prior art sulfoximine preparations. The novel N- (orthoand para-nitrobenzoyl)-sulfoximines of formula I may be hydrolyzed, under either acid or alkaline conditions to obtain free sulfoximines of the formula IV;

wherein R and R are as described above. The novel sulfoximines of this invention having formula I and the free sulfoximines having formula IV. produced by the novel process of this invention are useful as intermediates in the preparation of known. pharmacologically active Nsubstituted aminoalkyl-S,Sdiphenylsulfoximines.

1 Claim, 2 Drawing Figures PREPARATION OF FREE SULFOXIMINES BY HYDROLYSIS OF N-(ORTHO- AND PARA-NITROBEN ZOYL )-SULFOXIMINES This is a division of application Ser. No. 351,112, filed Apr. 13, 1973, now US. Pat. No. 3,868,418.

SUMMARY OF THE INVENTION This invention relates to novel intermediates having the general formula 1:

wherein R and R represent an aliphatic radical having from I to 3 carbon atoms, a phenyl radical, or a monosubstituted phenyl radical, and to a simple, safe process for producing intermediates I by reacting a sulfoxide having the formula II:

R'R s= n wherein R and R are as described above, with an O- acylnitrobenzhydroxamic acid of the general formula III:

III

wherein R represents methyl or ethyl. The N-(orthoand paranitrobenzoyl)-sulfoximines of formula I may be hydrolyzed, under either acid or alkaline conditions to obtain free sulfoximines of the formula IV:

wherein R and R are as described above. The novel sulfoximines of this invention having formula I and the free sulfoximines having formula IV produced by the novel process of this invention are useful as intermediates in the preparation of known, pharmacologically active N-substituted aminoalkyl-S,S-diphenylsulfoximines.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE INVENTION sulfoximines of the general type prepared by the novel process of this invention were not discovered until 1949 (H. R. Bently and collaborators, Nature 164, 438 (1949)). Recently, a number of papers dealing with the synthesis. the mode of reaction and the structure of the sulfoximines, have appeared. In addition, interesting pharmacological properties of some sulfoximines have also been described, as for example, in US. Pat. No. 3,637,664, where N-substituted aminoalkyl- S,S-diphenylsulfoximines are described as exhibiting broncholyticantispasmodic activity.

The laboratory method generally adopted for the preparation of the subject sulfoximines consists in the thermal or photolytic decomposition of hydrazoic acid produced in situ, or the decomposition of organic azides, in the presence of sulfoxides. During such preparations, the tendency of the hydrazoic acid and of the azides to decompose explosively on contact or when struck or heated compels the utilization of extensive safety measures during this reaction. Even with the necessary precautions, spontaneous explosions occur repeatedly when these compounds are handled. The potential danger of this reaction to the production facilities and -to personnel engaged in the preparation of these compounds has, heretofore, made semi-industrial or technical use of the sulfoximine products undesirable in most respects.

The present invention relates to a novel, simple process for the production of N-substituted sulfoximines, which can be utilized safely on an industrial scale, without risk to apparatus or personnel. Additionally, the

present invention relates to several novel compounds prepared according to the novel process as well as to a process for simple transformation of these novel N-substituted sulfoximines into the free sulfoximines, which can be in turn utilized to prepare known, pharmacologically active N-substituted sulfoximines.

The process according to the invention for the production of novel N-substituted sulfoximines consists in reacting sulfoxides having the formula II:

R'R*s=0 n lII wherein R represents methyl or ethyl, according to the reaction scheme illustrated in FIG. I of the drawings. In this connection R and R may be alkyl groups with I 3 C-atoms, phenyl radicals or monosubstituted phenyl radicals; R represents methyl or ethyl.

The N-nitrobenzoyl sulfoximines III obtained can be hydrolysed under both acid and alkaline conditions according to the invention to form the free sulfoximines having the formula IV, wherein the S=N bond is maintained. This reaction is illustrated in FIG. II of the drawings.

The free sulfoximines IV obtained can be used as intermediate products for the preparation of other N- substituted sulfoximines, that is, the N-substituted ami- 3 noalkyl-S,S-diphenylsulfoximines described in US. Pat. No. 3,637,664. These last mentioned sulfoximines of US. Pat. No. 3,637,664 exhibit broncholyticantispasmodic activity and are useful in treating conditions generally associated with bronchial diseases.

The sulfoxides used as the starting substances for the process of this invention can either be commercially obtained or can be prepared according to generally known methods. Nitrobenzhydroxamic acids are obtained from nitrobenzoic acid derivatives and hydroxylamine; the o-acyl-compounds can be prepared by reaction of hydroxamic acids with acid halides or acid anhydrides.

The reaction of a sulfoxide and a hydroxamic acid ester according to the invention is carried out in the melt preferably, but it is also possible to perform this step in a solvent. The reaction temperature and heating time depend upon the individual components and the properties thereof, above all upon their melting points. Thus, the reaction temperatures range from about 70C to 200C; the reaction times are about one or more hours, again depending upon reactants. When using high boiling sulfoxides, it is preferable to provide a vacuum; the acetic acid or propionic acid forming in the course of the reaction thus distills off. Upon completion of the reaction, the reaction mixture is allowed to cool, and a solvent is added in which the corresponding sulfoximines are sparingly soluble, while providing utmost solubility for the impurities. For example lower alcohols or ethyl acetate are used. The corresponding sulfoximines are isolated by means of suction or centrifuging. and possibly purified by recrystallization.

The N-acyl sulfoximines obtained by the process of this invention surprisingly can be hydrolysed very easily, the S=N bond being retained. Hydrolysis can be performed with mineral acids or with aqueous or alcoholic alkali. Preferably methanolic KOH is used, with a heating time of 35 60 minutes sufficing for completing the hydrolysis. For isolating the free sulfoximines, the reaction mixture is diluted with water and the sulfoximine bases are extracted by means of a solvent immiscible with water. After having distilled off the solvent, the sulfoximines are left in the form of a residue; for purification, either a sparingly soluble salt is produced, such as the hydrochloride, by introducing HCl gas into the solution of the corresponding sulfoximine base in ethyl acetate, or the sulfoximine base is distilled or recrystallized.

Hydrolysis of the N-acyl sulfoximines can also be performed without isolation, directly after reaction of the sulfoxide with the nitrobenzhydroxamic acid ester, in

the same reaction vessel.

in order to further illustrate this invention, the following examples are given:

EXAMPLE 1 405 g (2 moles) of diphenyl sulfoxide and 493 g (2.2 moles) of O-acetyl-p-nitrobenzhydroxamic acid are mixed, transferred into a th rec-necked flask and melted in he oil bath while stirring. Subsequently a water jet vacuum is provided and the melt heated for 6 hours to l30C-l40C of oil bath temperature, while stirring. The principal amount of the acetic acid formed thus distils off. Upon completion of the reaction the mixture is allowed to cool to 60C70C, and 5 liters of isopropyl alcohol are added. The N-(p-nitrobenzoyl)- diphenylsulfoximine crystallizes out on standing and further cooling; it is sucked off and washed. The yield 4 amounts to 535 g (73 7c of theory). N-(p-nitrobenzoyl)-S,S-diphenyl sulfoximine forms colorless crystals, M.P. l61C.

EXAMPLE 2 22.4 g (0.l mole) of O-acetyl-p-nitrobenzhydroxamic acid are dissolved in 150 ml of dimethyl sulfoxide, and the solution is heated in the oil bath to Cl00C for 15 hours. Subsequently 300 ml of water are added. On cooling, 22 g (91 of theory) of N-(p-nitrobenzoyl )-S,S-dimethylsulfoximine crystallize out. Colorless crystals, MP. of l90C, form.

EXAMPLE 3 24.6 g (0.11 mole) of O-acetyl-p-nitrobenzhydroxamic acid are heated with 14 g (0.1 mole) of methylphenyl-sulfoxide to l30C-l40C for 6 hours, while stirring. Upon completion of the reaction the mixture is heated with 250 ml of isopropanol, the solution treated with coal and cooled. 13.6 g (45 of theory) of N-(pnitrobenzoyl)-S-phenyl-S-methyl-sulfoximine crystallize out. The substance melts at [44C.

EXAMPLE 4 23.8 g (0.1 mole) of O-propionyl-p-nitrobenzhydroxamic acid and 20.2 g (0.1 mole) of diphenylsulfoxide are heated in the oil bath to l35C-140C for 12 hours, while stirring. The cooled reaction mixture is boiled up with 250 ml of isopropanol. On cooling and standing, N-(p-nitro-benzoyl)-S,S-diphenylsulfoximine crystallizes out.

The yield amounts to M5 g (40 of theory).

EXAMPLE 5 366 g (l mole) of N-(p-nitrobenzoyl)-S,S-diphenylsulfoximine are heated to reflux for l hour in 3 liters of 10 methanolic KOH. Subsequently the principal amount of methanol is distilled off, and 5 liters of water are added to the residue. The diphenyl sulfoximine is extracted with dichloromethane, the organic phase is dried, and the solvent distilled off. The remaining residue is taken up in 800 ml of ethyl acetate and the hydrochloride precipitated by means of ethyl acetate/HCl. The yield amounts to 2l9 g (86 of theory). Diphenyl sulfoximine hydrochloride forms colorless crystals, M.P. 238C 240C.

EXAMPLE 6 As in Example I, 405 g (2 moles) of diphenyl sulfoxide are reacted with 493 g (2.2 moles) of O-acetyl'pnitrobenzhydroxamie acid at l30C-l 40C. Upon completion of the reaction the N-aeyl compound is hydrolysed directly (according to Example 5): 3 liters of 10 methanolic KOH are added and the mixture heated under reflux for one hour. The principal amount of the methanol is removed, 6 liters of water are added, and the mixture is extracted with dichloromethane. The residue of the dichloromethane phase is taken up in ethyl acetate and the diphenyl sulfoximine hydrochloride precipitated by means of ethyl acetate/HCl. The yield amounts to 342 g (68 of theory).

EXAMPLE 7 24.6 g (0.ll mole) of O-acetyl-p-nitrobenzhydroxamic acid are heated for 5 hours with 26.2 g (0.1 mole) of Di-(p-methoxyphenyl)-sulfoxide to C. while stirring. Upon completion of the reaction ml of l0 7( methanolic KOH are added and the mixture is boiled EXAMPLE 8 24.6 g (0.11 mole) of O-acetyl-o-nitrobenzhydroxamic acid are heated with 20.2 g (0.1 mole) of diphenyl sulfoxide to l35C in the oil bath for 8 hours, while stirring. Then hydrolysation is performed as described in Example 6, and the hydrochloride of the diphenyl sulfoximine precipitated. The yield amounts to 4.3 g (17 of theory).

We claim:

1. A process for the production of free sulfoximines of the general formula IV, and the acid addition salts thereof:

wherein R and R represent an aliphatic radical having from 1 to 3 carbon atoms, a phenyl radical, or a paramethoxy phenyl radical, which comprises subjecting N-(ortho or paranitrobenzoyl)sulfoximines of the general formula 1:

wherein R and R are as described above, to hydrolysis under either acid or alkaline conditions. 

1. A PROCESS FOR THE PRODUCTION OF FREE SULFOXIMINES OF THE GENERAL FORMULA 1V, AND THE ACID ADDITION SALTS THEREOF: R1-S(=O)(=NH)-R2 WHEREIN R1 AND R2 REPRESENT AN ALIPHATIC RADICAL HAVING FROM 1 TO 3 CARBON ATOMS, A PHENYL RADICAL, OR A PARA-METHOXY PHENYL RADICAL, WHICH COMPRISES SUBJECTING N-(ORTHO OR PARANITROBENZOYL)SULFOXIMINES OF THE GENERAL FORMULA I: ((O2N-)PHENYL)-CO-N=S(=O)(-R1)-R2 WHEREIN R1 AND R2 ARE AS DESCRIBED ABOVE, TO HYDROLYSIS UNDER EITHER ACID OR ALKALINE CONDITIONS. 